🫁 ROX Index (HFNC Outcome)
Predict high-flow nasal cannula success with the ROX index in acute hypoxaemic respiratory failure.
ROX Index (HFNC Outcome)
SpO₂ (%)
FiO₂ (fraction)
Respiratory rate (/min)
When to use
Monitor response to HFNC and flag impending failure.
How it works
ROX = (SpO₂% / FiO₂) / respiratory rate. ≥ 4.88 predicts success; < 3.85 suggests failure.
Key points
- Assess at ~2, 6 and 12 hours of HFNC.
- Persistently low values warrant considering intubation.
- Combines oxygenation and respiratory drive in one number.
References
Decision support for licensed clinicians only; not a substitute for clinical judgement, diagnosis or local protocols.